1. Field of the Invention
The present invention relates to an endoscope fogging prevention heater unit which prevents fogging which occurs in an endoscope, and an endoscope.
2. Description of the Related Art
A distal end portion of an endoscope insertion portion is inserted in a humid environment, for example, in a body cavity. If the distal end portion is inserted in this environment and the temperature of the inserted distal end portion is lower than the temperature of the environment, the surface of an optical member (e.g. a lens cover) provided in the distal end portion may fog because of a temperature difference. This fog may prevent, for example, an observation or a treatment.
Thus, to counter such fog, the endoscope has a fogging prevention heater unit which is provided inside of the distal end portion of the insertion portion and which prevents the fog. This fogging prevention heater unit has a heater which heats the inside to prevent fogging, a temperature sensor which measures the temperature of the inside, and a substrate on which the heater and the temperature sensor are mounted.
Such a fogging prevention heater unit has been disclosed in, for example, Jpn. Pat. Appin. KOKAI Publication No. 2006-282. In Jpn. Pat. Appin. KOKAI Publication No. 2006-282, heating by the heater is controlled on the basis of the temperature which the temperature sensor detects.